The present invention relates generally to vehicles, and more particularly to a method for operating a vehicle having variable-speed left-side and right-side propulsion units.
Vehicles having variable-speed left-side and right-side propulsion units include those having traction-type propulsion units and those having non-traction-type propulsion units. Non-traction-type propulsion units include, without limitation, left-side and right-side aircraft engines and left-side (meaning positioned more to the left side than the right side) and right-side (meaning positioned more to the right side than the left side) boat and submarine propellers and/or thrusters. Traction-type propulsion units engage a solid surface and include left-side and right-side wheel and motor units and left-side and right-side track and motor units. Tracked vehicles include military tanks, bulldozers, and small robotic vehicles (such as those used by police bomb squads).
It is known to remotely control a wheeled vehicle using left and right joysticks. Moving the left joystick forward/back controls the forward/back rotational speed of left-side front and rear wheels. Likewise, moving the right joystick forward/back controls the forward/back rotational speed of right-side front and rear wheels. It is difficult to precisely manually control the positions of the left and right joysticks to move the vehicle in a straight line. It also is known to control a tracked vehicle using a single joystick. What is needed is an improved method for operating a vehicle having variable-speed left-side and right-side propulsion units.
A first method of the invention is for operating a tracked vehicle having left and right tracks. The vehicle has a left-track motor adapted to provide variable-speed forward and reverse motion to the left track, and the vehicle has a right-track motor adapted to provide variable-speed forward and reverse motion to the right track. The left-track motor is controlled by a first output signal from a left joystick, and the right-track motor is controlled by a second output signal from a right joystick. The first method includes steps a) and b). Step a) includes modifying at least one of the first and second output signals to create a substantially identical output signal for the left and right joysticks when the first and second output signals are within a predetermined tolerance. Step b) includes controlling the left-track and right-track motors with the identical output signal when the first and second output signals are within the predetermined tolerance.
A second method of the invention is for operating a vehicle. The vehicle has a left-side traction unit adapted to provide variable-speed forward and reverse motion to the left side of the vehicle, and the vehicle has a right-side traction unit adapted to provide variable-speed forward and reverse motion to the right side of the vehicle. The left-side traction unit is controlled by a first output signal from a first manual controller, and the right-side traction unit is controlled by a second output signal from a second manual controller. The second method includes steps a) and b). Step a) includes modifying at least one of the first and second output signals to create a substantially identical output signal for the first and second manual controllers when the first and second output signals are within a predetermined tolerance. Step b) includes controlling the left-side and right-side traction units with the identical output signal when the first and second output signals are within the predetermined tolerance.
A third method of the invention is for operating a vehicle having variable-speed left-side and right-side propulsion units. The left-side propulsion unit is controlled by a first output signal from a first manual controller, and the right-side propulsion unit is controlled by a second output signal from a second manual controller. The method includes steps a) and b). Step a) includes modifying at least one of the first and second output signals to create a substantially identical output signal for the first and second manual controllers when the first and second output signals are within a predetermined tolerance. Step b) includes controlling the left-side and right-side propulsion units with the identical output signal when the first and second output signals are within the predetermined tolerance.
Several benefits and advantages are derived from one or more of the methods of the invention. Controlling the left-side and right-side propulsion units (such as left-side and right-side traction units such as left-track and right-track motors providing motion to respective left and right tracks) with a substantially identical output signal when the first and second output signals are within a predetermined tolerance moves the vehicle in a straight line despite differences (up to the predetermined tolerance) in the positions of the first and second manual controllers (such as left and right joysticks). Such control anticipates such differences (up to the predetermined tolerance) as indicating the user is trying to move the vehicle in a straight line.